Surgical fluid management systems and methods

ABSTRACT

A fluid management system for use with a fluid reservoir includes an inflow pump and an outflow pump. The inflow pump is connectable to a probe for delivering a distention fluid to a body cavity. The outflow pump removes the distention fluid through the same probe, thus establishing a re-circulating volume of distention fluid within the body cavity. The removed fluid is filtered and returned to a fluid reservoir for eventual recycling to the body cavity. A controller adjusts the flow rates of the inflow pump and the outflow pump to maintain a pre-selected fluid pressure or volume within the body cavity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/505,973, filed on Jul. 9, 2019, which application is a continuationof U.S. patent application Ser. No. 14/962,872, filed on Dec. 8, 2015,now U.S. Pat. No. 10,368,912, which application is a continuation ofU.S. patent application Ser. No. 13/534,908, filed on Jun. 27, 2012, nowU.S. Pat. No. 9,233,193, which application claims the benefit ofprovisional application No. 61/502,750, filed on Jun. 29, 2011, and alsothe benefit of provisional application No. 61/503,497, filed on Jun. 30,2011, the full disclosures of which are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates surgical fluid management systems andmethods, for example for use in distending the uterine cavity to allowcutting and extraction of uterine fibroid tissue, polyps and otherabnormal uterine tissue.

BACKGROUND

Uterine fibroids are non-cancerous tumors that develop in the wall ofuterus. Such fibroids occur in a large percentage of the femalepopulation, with some studies indicating up to 40 percent of all womenhave fibroids. Uterine fibroids can grow over time to be severalcentimeters in diameter and symptoms can include menorrhagia,reproductive dysfunction, pelvic pressure and pain.

One current treatment of fibroids is hysteroscopic resection ormyomectomy which involves transcervical access to the uterus with ahysteroscope together with insertion of a cutting instrument through aworking channel in the hysteroscope. The cutting instrument may be amechanical tissue cutter or an electrosurgical resection device such asa cutting loop. Mechanical cutting devices are disclosed in U.S. Pat.Nos. 7,226,459; 6,032,673 and 5,730,752 and U.S. Published Patent Appl.2009/0270898. An electrosurgical cutting device is disclosed in U.S.Pat. No. 5,906,615.

In a myomectomy or hysteroscopic resection, the initial step of theprocedure includes distention of the uterine cavity to create a workingspace for assisting viewing through the hysteroscope. In a relaxedstate, the uterine cavity collapses with the uterine walls in contactwith one another. A fluid management system is used to distend theuterus to provide a working space wherein a fluid is administeredthrough a passageway in the hysteroscope under sufficient pressure toexpand or distend the uterine cavity. The fluids used to distend theuterus are typically liquid aqueous solutions such as a saline solutionor a sugar-based aqueous solution.

In some RF electrosurgical resection procedures, the distending fluid isa non-conductive aqueous solution to limit RF current conduction.

One particular concern is the fact that fluid management systemstypically administer the fluid under a pressure of up to 100 mm Hg ormore which results in a significant risk that the distending fluid maybe taken up by a cut blood vessel exposed in the uterine cavity. Suchunwanted fluid uptake is known as intravasation, which can lead toserious complications and even death. For this reason, fluid managementsystems have been developed to monitor the patient's fluid uptake on acontinuous basis during a procedure, typically using complicated systemsthat capture, collect and weigh distending fluids that flow through theuterine cavity.

For these reasons, it would be desirable to provide improved fluidmanagement systems and methods for their use for performinghysteroscopic fibroid resection, myomectomy, or other similar procedureswhich require fluid distension. The systems and methods preferablyutilize a limited volume of distending fluid and will provide for analarm and/or system shut down when it appears that excessive fluid hasbeen lost from the system. At least some of these objectives will be metby the inventions described herein below.

SUMMARY

The present invention provides improved fluid management systems andmethods for use in performing hysteroscopic fibroid resection,myomectomy, and a variety of other tissue removal procedures performedin a re-circulating distension fluid environment. The fluid managementsystems of the present invention are adapted to utilize an initialvolume of distending fluid which is recovered, filtered, andre-circulated to the patient. Thus, by limiting the initial volume ofdistending fluid used in the system, the risk of excess fluid uptake bythe patient can be reduced. The systems and methods also provide forconvenient and reliable detection of fluid loss to alert the user and/orautomatically shut down the system.

In the first aspect of the present invention, a fluid management systemis provided for use with a fluid reservoir and a probe. The fluidreservoir may be a conventional fluid drip bag which is adapted toreceive the return of a filtered, re-circulating distending fluid fromthe patient. The probe will typically be adapted for tissue resection,including cutting blades, radiofrequency (RF) ablation electrodes orelements, rotating burrs, drills, or the like. An exemplary fluidremoval probe includes an outer sleeve and an inner cutting sleeve whichis reciprocatably mounted in the outer sleeve. The outer sleeve has acutting window which can be engaged against fibroid or other tissue tobe resected. By pressing the window against the tissue, the fibroid orthe tissue intrudes into the window, and the inner cutting sleeve can bedistally advanced to severe the tissue.

The fluid management systems of the present invention will beconnectable both to the fluid reservoir and to the probe, where theprobe will typically have lumens both for delivering the distendingfluid and to a body space or potential space having the tissue to beresected, such as a uterus having fibroids. An inflow pump isconnectable to an inflow fluid lumen of the probe for providing aninflow of the distending fluid to the body space or potential space. Anoutflow pump of the system is connectable to a fluid outflow lumen ofthe probe for removing fluid from the space and returning the removedfluid to the reservoir. The system further includes a filter arrangementfor removing waste from the removed fluid before returning the removedfluid to the reservoir. A controller is also provided for adjusting theflow rates of the inflow pump and of the outflow pump. By properlycontrolling and adjusting these flow rates, a controller can maintain apre-selected distended fluid pressure and/or fluid volume in the bodyspace or potential space.

In a first exemplary embodiment, the controller is configured to controlthe inflow and outflow of the first and second pumps, which aretypically positive displacement pumps, to maintain a target pressurewithin the body space or potential space. For fibroid resection in auterus, the pressure will typically be in the range from 20 mmHg to 200mmHg. More generally, the range may be from 10 mmHg to 400 mmHg forother treatment modalities.

Alternatively, the controller may be configured in a flow control mode,wherein the first and second pumps cooperate to deliver fluid to thespace within flow rates selected to control the volume of fluidaccumulating in the body space or potential space. For treatment offibroids or other conditions within the uterus, the flow rate of fluid,typically saline, will typically be from 200 ml/min to 1000 ml/min.

When controlling body space pressure, the system will typically furtherinclude at least one pressure sensor capable of providing a pressuresignal indicating fluid pressure in the space or potential space. Forexample, the pressure sensor could be located in the fluid input lumenof the probe, preferably near a distal tip of the lumen. To maintain adesired volume of fluid in the body space or potential space, the systemwill typically include flow measurement sensors for both the inflow flowrate and the outflow flow rate, where the flow rates over time can beintegrated to calculate the total fluid volume in and the total fluidvolume out over time.

In a still further alternate embodiment, the fluid management system maybe configured to further monitor both inflow pump pressure and outflowpump pressure. If the inflow pressure and outflow pressure are found todiffer by more than a pre-determined minimum amount, there may beblockages or other malfunctions of the system. In such cases, the systemcan alert the user and/or automatically shut down the system.

The system may have other components and features, for example, thesystem may further comprise a probe and optionally a disposable tubingset for delivering fluid to the probe, where the tubing set includes atleast one pulse dampener. The tubing set will typically also includetubes and connectors for recovering fluid from the probe and returningthe fluid to the reservoir.

The systems of the present invention may still further comprise awindow-closing mechanism on the probe converts to its window-closedconfiguration in response to idling or other cessation of thereciprocation of the inner cutting tube.

In a still further aspect of the present invention, methods are providedfor monitoring delivery and recovery of a distending fluid to a body orpotential space to detect loss of that fluid beyond an expected loss.Additionally, a reference volume of the distending fluid within a supplycontainer is recorded. The distending fluid is then directed into thebody space or potential space, and an outflow of the fluid volume fromthe space is recovered. The recovered fluid is filtered andre-circulated to the supply container to provide a replenished volume. Afluid deficit may be then calculated by subtracting the replenishedfluid volume from the initial reference volume. While at the beginningof a treatment, the replenished volume will be expected to besignificantly lower than the initial volume, after some time a steadystate will be reached in which a smaller, generally constant fluiddeficit is found. The fluid deficit results, of course, from fluidpresent within the system as well as fluid present within the body spaceor the potential space. Thus, the methods of the present invention areall optionally comprise determining and recording both the systemcapacity volumes and the volumes of the potential space. By taking thosevolumes into account, the difference between the referenced volume andthe replenished volume will be further reduced. The system volume may bedetermined, for example, by priming the supply tubing set and a probe orother surgical device with the distending fluid. The volume of the bodyor potential space may be determined by introducing a distending fluidinto the body space and measuring the volume of the introduced fluid.Alternatively, the volume of the body space could be determined byimaging means.

In further embodiments, the methods of the present invention maycomprise sealing an access to the body space, for example the cervixwhen treating a uterus, to prevent the loss of distending fluid from thebody cavity or space. Alternatively, fluid which is lost through theaccess to the body space may be captured and measured in order toaccount for it by adding that fluid volume to the replenished fluidvolume. The methods further provide for monitoring and signaling a fluiddeficit which has become excessive, either on an intermittent orcontinuous basis, where the signal may be at least one of visual, auraland tactile.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view of an assembly including a hysteroscope and atissue-cutting device corresponding to the invention that is insertedthrough the working channel of the hysteroscope.

FIG. 2 is a schematic perspective view of a fluid management system usedfor distending the uterus and for assisting in electrosurgical tissuecutting and extraction.

FIG. 3 is a cross-sectional view of the shaft of the hysteroscope ofFIG. 1 showing various channels therein.

FIG. 4 is a schematic side view of the working end of theelectrosurgical tissue-cutting device of FIG. 1 showing an outer sleeveand a reciprocating inner sleeve and an electrode arrangement.

FIG. 5 is a schematic perspective view of the working end of the innersleeve of FIG. 4 showing its electrode edge.

FIG. 6A is a schematic cut-away view of a portion of outer sleeve, innerRF cutting sleeve and a tissue-receiving window of the outer sleeve.

FIG. 6B is a schematic view of a distal end portion another embodimentof inner RF cutting sleeve.

FIG. 7A is a cross sectional view of the inner RF cutting sleeve of FIG.6B taken along line 7A-7A of FIG. 6B.

FIG. 7B is another cross sectional view of the inner RF cutting sleeveof FIG. 6B taken along line 7B-7B of FIG. 6B.

FIG. 8 is a schematic view of a distal end portion of another embodimentof inner RF cutting sleeve.

FIG. 9A is a cross sectional view of the RF cutting sleeve of FIG. 8taken along line 9A-9A of FIG. 8.

FIG. 9B is a cross sectional view of the RF cutting sleeve of FIG. 8taken along line 9B-9B of FIG. 8.

FIG. 10A is a perspective view of the working end of the tissue-cuttingdevice of FIG. 1 with the reciprocating RF cutting sleeve in anon-extended position.

FIG. 10B is a perspective view of the tissue-cutting device of FIG. 1with the reciprocating RF cutting sleeve in a partially extendedposition.

FIG. 10C is a perspective view of the tissue-cutting device of FIG. 1with the reciprocating RF cutting sleeve in a fully extended positionacross the tissue-receiving window.

FIG. 11A is a sectional view of the working end of the tissue-cuttingdevice of FIG. 10A with the reciprocating RF cutting sleeve in anon-extended position.

FIG. 11B is a sectional view of the working end of FIG. 10B with thereciprocating RF cutting sleeve in a partially extended position.

FIG. 11C is a sectional view of the working end of FIG. 10C with thereciprocating RF cutting sleeve in a fully extended position.

FIG. 12A is an enlarged sectional view of the working end oftissue-cutting device of FIG. 11B with the reciprocating RF cuttingsleeve in a partially extended position showing the RF field in a firstRF mode and plasma cutting of tissue.

FIG. 12B is an enlarged sectional view of the working end of FIG. 11Cwith the reciprocating RF cutting sleeve almost fully extended andshowing the RF fields switching to a second RF mode from a first RF modeshown in FIG. 12.

FIG. 12C is an enlarged sectional view of the working end of FIG. 11Cwith the reciprocating RF cutting sleeve again almost fully extended andshowing the explosive vaporization of a captured liquid volume to expelcut tissue in the proximal direction.

FIG. 13 is an enlarged perspective view of a portion of the working endof FIG. 12C showing an interior chamber and a fluted projecting element.

FIG. 14 is a sectional view of the working end of FIG. 12C showing aninterior chamber and a variation of a projecting element.

FIG. 15 is a sectional view of the working end of FIG. 12C showing aninterior chamber and a variation of a projecting element configured toexplosively vaporize the captured liquid volume.

FIG. 16 is a schematic view of a system for fibroid removal including afluid management system.

FIG. 17 is a longitudinal sectional view of a working end similar tothat of FIGS. 11A-11C showing a maximum cut volume.

FIG. 18 is a schematic view of a fluid management system correspondingto the invention.

FIG. 19 is a box diagram showing various pump and filter components ofthe fluid management system of FIG. 18.

FIG. 20 is a view of the distal end of a cutting probe showing anelectrical sensor for sensing tissue contact coupled to a controller ofa fluid management system as in FIG. 18.

DETAILED DESCRIPTION

FIG. 1 illustrates an assembly that comprises an endoscope 50 used forhysteroscopy together with a tissue-extraction device 100 extendingthrough a working channel 102 of the endoscope. The endoscope orhysteroscope 50 has a handle 104 coupled to an elongated shaft 105having a diameter of 5 mm to 7 mm. The working channel 102 therein maybe round, D-shaped or any other suitable shape. The endoscope shaft 105is further configured with an optics channel 106 and one or more fluidinflow/outflow channels 108 a, 108 b (FIG. 3) that communicate withvalve-connectors 110 a, 110 b configured for coupling to a fluid inflowsource 120 thereto, or optionally a negative pressure source 125 (FIGS.1-2). The fluid inflow source 120 is a component of a fluid managementsystem 126 as is known in the art (FIG. 2) which comprises a fluidcontainer 128 and pump mechanism 130 which pumps fluid through thehysteroscope 50 into the uterine cavity. As can be seen in FIG. 2, thefluid management system 126 further includes the negative pressuresource 125 (which can comprise an operating room wall suction source)coupled to the tissue-cutting device 100. The handle 104 of theendoscope includes the angled extension portion 132 with optics to whicha videoscopic camera 135 can be operatively coupled. A light source 136also is coupled to light coupling 138 on the handle of the hysteroscope50. The working channel 102 of the hysteroscope is configured forinsertion and manipulation of the tissue-cutting and extracting device100, for example to treat and remove fibroid tissue. In one embodiment,the hysteroscope shaft 105 has an axial length of 21 cm, and cancomprise a 0° scope, or 15° to 30° scope.

Still referring to FIG. 1, the tissue-cutting device 100 has a highlyelongated shaft assembly 140 configured to extend through the workingchannel 102 in the hysteroscope. A handle 142 of the tissue-cuttingdevice 100 is adapted for manipulating the electrosurgical working end145 of the device. In use, the handle 142 can be manipulated bothrotationally and axially, for example, to orient the working end 145 tocut targeted fibroid tissue. The tissue-cutting device 100 hassubsystems coupled to its handle 142 to enable electrosurgical cuttingof targeted tissue. A radio frequency generator or RF source 150 andcontroller 155 are coupled to at least one RF electrode carried by theworking end 145 as will be described in detail below. In one embodimentshown in FIG. 1, an electrical cable 156 and negative pressure source125 are operatively coupled to a connector 158 in handle 142. Theelectrical cable couples the RF source 150 to the electrosurgicalworking end 145. The negative pressure source 125 communicates with atissue-extraction channel 160 in the shaft assembly 140 of the tissueextraction device 100 (FIG. 4).

FIG. 1 further illustrates a seal housing 162 that carries a flexibleseal 164 carried by the hysteroscope handle 104 for sealing the shaft140 of the tissue-cutting device 100 in the working channel 102 toprevent distending fluid from escaping from a uterine cavity.

In one embodiment as shown in FIG. 1, the handle 142 of tissue-cuttingdevice 100 includes a motor drive 165 for reciprocating or otherwisemoving a cutting component of the electrosurgical working end 145 aswill be described below. The handle 142 optionally includes one or moreactuator buttons 166 for actuating the device. In another embodiment, afootswitch can be used to operate the device. In one embodiment, thesystem includes a switch or control mechanism to provide a plurality ofreciprocation speeds, for example 1 Hz, 2 Hz, 3 Hz, 4 Hz and up to 8 Hz.Further, the system can include a mechanism for moving and locking thereciprocating cutting sleeve in a non-extended position and in anextended position. Further, the system can include a mechanism foractuating a single reciprocating stroke.

Referring to FIGS. 1 and 4, an electrosurgical tissue-cutting device hasan elongate shaft assembly 140 extending about longitudinal axis 168comprising an exterior or first outer sleeve 170 with passageway orlumen 172 therein that accommodates a second or inner sleeve 175 thatcan reciprocate (and optionally rotate or oscillate) in lumen 172 to cuttissue as is known in that art of such tubular cutters. In oneembodiment, the tissue-receiving window 176 in the outer sleeve 170 hasan axial length ranging between 10 mm and 30 mm and extends in a radialangle about outer sleeve 170 from about 45° to 210° relative to axis 168of the sleeve. The outer and inner sleeves 170 and 175 can comprise athin-wall stainless steel material and function as opposing polarityelectrodes as will be described in detail below. FIGS. 6A-8 illustrateinsulative layers carried by the outer and inner sleeves 170 and 175 tolimits, control and/or prevent unwanted electrical current flows betweencertain portions go the sleeve. In one embodiment, a stainless steelouter sleeve 170 has an O.D. of 0.143″ with an I.D. of 0.133″ and withan inner insulative layer (described below) the sleeve has a nominalI.D. of 0.125″. In this embodiment, the stainless steel inner sleeve 175has an O.D. of 0.120″ with an I.D. of 0.112″. The inner sleeve 175 withan outer insulative layer has a nominal O.D. of about 0.123″ to 0.124″to reciprocate in lumen 172. In other embodiments, outer and or innersleeves can be fabricated of metal, plastic, ceramic of a combinationthereof. The cross-section of the sleeves can be round, oval or anyother suitable shape.

As can be seen in FIG. 4, the distal end 177 of inner sleeve 175comprises a first polarity electrode with distal cutting electrode edge180 about which plasma can be generated. The electrode edge 180 also canbe described as an active electrode during tissue cutting since theelectrode edge 180 then has a substantially smaller surface area thanthe opposing polarity or return electrode. In one embodiment in FIG. 4,the exposed surfaces of outer sleeve 170 comprises the second polarityelectrode 185, which thus can be described as the return electrode sinceduring use such an electrode surface has a substantially larger surfacearea compared to the functionally exposed surface area of the activeelectrode edge 180.

In one aspect of the invention, the inner sleeve or cutting sleeve 175has an interior tissue extraction lumen 160 with first and secondinterior diameters that are adapted to electrosurgically cut tissuevolumes rapidly—and thereafter consistently extract the cut tissuestrips through the highly elongated lumen 160 without clogging. Nowreferring to FIGS. 5 and 6A, it can be seen that the inner sleeve 175has a first diameter portion 190A that extends from the handle 142(FIG. 1) to a distal region 192 of the sleeve 175 wherein the tissueextraction lumen transitions to a smaller second diameter lumen 190Bwith a reduced diameter indicated at B which is defined by the electrodesleeve element 195 that provides cutting electrode edge 180. The axiallength C of the reduced cross-section lumen 190B can range from about 2mm to 20 mm. In one embodiment, the first diameter A is 0.112″ and thesecond reduced diameter B is 0.100″. As shown in FIG. 5, the innersleeve 175 can be an electrically conductive stainless steel and thereduced diameter electrode portion also can comprise a stainless steelelectrode sleeve element 195 that is welded in place by weld 196 (FIG.6A). In another alternative embodiment, the electrode and reduceddiameter electrode sleeve element 195 comprises a tungsten tube that canbe press fit into the distal end 198 of inner sleeve 175. FIGS. 5 and 6Afurther illustrates the interfacing insulation layers 202 and 204carried by the first and second sleeves 170, 175, respectively. In FIG.6A, the outer sleeve 170 is lined with a thin-wall insulative material200, such as PFA, or another material described below. Similarly, theinner sleeve 175 has an exterior insulative layer 202. These coatingmaterials can be lubricious as well as electrically insulative to reducefriction during reciprocation of the inner sleeve 175.

The insulative layers 200 and 202 described above can comprise alubricious, hydrophobic or hydrophilic polymeric material. For example,the material can comprise a bio-compatible material such as PFA,TEFLON®, polytetrafluroethylene (PTFE), FEP (Fluorinatedethylenepropylene), polyethylene, polyamide, ECTFE(Ethylenechlorotrifluoro-ethylene), ETFE, PVDF, polyvinyl chloride orsilicone.

Now turning to FIG. 6B, another variation of inner sleeve 175 isillustrated in a schematic view together with a tissue volume beingresected with the plasma electrode edge 180. In this embodiment, as inother embodiments in this disclosure, the RF source operates at selectedoperational parameters to create a plasma around the electrode edge 180of electrode sleeve 195 as is known in the art. Thus, the plasmagenerated at electrode edge 180 can cut and ablate a path P in thetissue 220, and is suited for cutting fibroid tissue and other abnormaluterine tissue. In FIG. 6B, the distal portion of the cutting sleeve 175includes a ceramic collar 222 which is adjacent the distal edge 180 ofthe electrode sleeve 195. The ceramic 222 collar functions to confineplasma formation about the distal electrode edge 180 and functionsfurther to prevent plasma from contacting and damaging the polymerinsulative layer 202 on the cutting sleeve 175 during operation. In oneaspect of the invention, the path P cut in the tissue 220 with theplasma at electrode edge 180 provides a path P having an ablated widthindicated at W, wherein such path width W is substantially wide due totissue vaporization. This removal and vaporization of tissue in path Pis substantially different than the effect of cutting similar tissuewith a sharp blade edge, as in various prior art devices. A sharp bladeedge can divide tissue (without cauterization) but applies mechanicalforce to the tissue and may prevent a large cross section slug of tissuefrom being cut. In contrast, the plasma at the electrode edge 180 canvaporize a path P in tissue without applying any substantial force onthe tissue to thus cut larger cross sections of slugs or strips oftissue. Further, the plasma cutting effect reduces the cross section oftissue strip 225 received in the tissue-extraction lumen 190B. FIG. 6Bdepicts a tissue strip to 225 entering lumen 190B which has such asmaller cross-section than the lumen due to the vaporizationn of tissue.Further, the cross section of tissue 225 as it enters the largercross-section lumen 190A results in even greater free space 196 aroundthe tissue strip 225. Thus, the resection of tissue with the plasmaelectrode edge 180, together with the lumen transition from the smallercross-section (190B) to the larger cross-section (190A) of thetissue-extraction lumen 160 can significantly reduce or eliminate thepotential for successive resected tissue strips 225 to clog the lumen.Prior art resection devices with such small diameter tissue-extractionlumen typically have problems with tissue clogging.

In another aspect of the invention, the negative pressure source 225coupled to the proximal end of tissue-extraction lumen 160 (see FIGS. 1and 4) also assists in aspirating and moving tissue strips 225 in theproximal direction to a collection reservoir (not shown) outside thehandle 142 of the device.

FIGS. 7A-7B illustrate the change in lumen diameter of cutting sleeve175 of FIG. 6B. FIG. 8 illustrates the distal end of a variation ofcutting sleeve 175′ which is configured with an electrode cuttingelement 195′ that is partially tubular in contrast to the previouslydescribed tubular electrode element 195 (FIGS. 5 and 6A). FIGS. 9A-9Bagain illustrate the change in cross-section of the tissue-extractionlumen between reduced cross-section region 190B′ and the increasedcross-section region 190A′ of the cutting sleeve 175′ of FIG. 8. Thus,the functionality remains the same whether the cutting electrode element195′ is tubular or partly tubular. In FIG. 8A, the ceramic collar 222′is shown, in one variation, as extending only partially around sleeve175 to cooperate with the radial angle of cutting electrode element195′. Further, the variation of FIG. 8 illustrates that the ceramiccollar 222′ has a larger outside diameter than insulative layer 202.Thus, friction may be reduced since the short axial length of theceramic collar 222′ interfaces and slides against the interfacinginsulative layer 200 about the inner surface of lumen 172 of outersleeve 170.

In general, one aspect of the invention comprises a tissue cutting andextracting device (FIGS. 10A-11C) that includes first and secondconcentric sleeves having an axis and wherein the second (inner) sleeve175 has an axially-extending tissue-extraction lumen therein, andwherein the second sleeve 175 is moveable between axially non-extendedand extended positions relative to a tissue-receiving window 176 infirst sleeve 170 to resect tissue, and wherein the tissue extractionlumen 160 has first and second cross-sections. The second sleeve 175 hasa distal end configured as a plasma electrode edge 180 to resect tissuedisposed in tissue-receiving window 176 of the first sleeve 170.Further, the distal end of the second sleeve, and more particularly, theelectrode edge 180 is configured for plasma ablation of a substantiallywide path in the tissue. In general, the tissue-extraction device isconfigured with a tissue extraction lumen 160 having a distal endportion with a reduced cross-section that is smaller than across-section of medial and proximal portions of the lumen 160.

In one aspect of the invention, referring to FIGS. 7A-7B and 9A-9B, thetissue-extraction lumen 160 has a reduced cross-sectional area in lumenregion 190A proximate the plasma cutting tip or electrode edge 180wherein said reduced cross section is less that 95%, 90%, 85% or 80%than the cross sectional area of medial and proximal portions 190B ofthe tissue-extraction lumen, and wherein the axial length of thetissue-extraction lumen is at least 10 cm, 20 cm, 30 cm or 40 cm. In oneembodiment of tissue-cutting device 100 for hysteroscopic fibroidcutting and extraction (FIG. 1), the shaft assembly 140 of thetissue-cutting device is 35 cm in length.

FIGS. 10A-10C illustrate the working end 145 of the tissue-cuttingdevice 100 with the reciprocating cutting sleeve or inner sleeve 175 inthree different axial positions relative to the tissue receiving window176 in outer sleeve 170. In FIG. 10A, the cutting sleeve 175 is shown ina retracted or non-extended position in which the sleeve 175 is at itproximal limit of motion and is prepared to advance distally to anextended position to thereby electrosurgically cut tissue positioned inand/or suctioned into in window 176. FIG. 10B shows the cutting sleeve175 moved and advanced distally to a partially advanced or medialposition relative to tissue cutting window 176. FIG. 10C illustrates thecutting sleeve 175 fully advanced and extended to the distal limit ofits motion wherein the plasma cutting electrode 180 has extended pastthe distal end 226 of tissue-receiving window 176 at which moment theresected tissue strip 225 in excised from tissue volume 220 and capturedin reduced cross-sectional lumen region 190A.

Now referring to FIGS. 10A-10C and FIGS. 11A-11C, another aspect of theinvention comprises “tissue displacement” mechanisms provided bymultiple elements and processes to “displace” and move tissue strips 225in the proximal direction in lumen 160 of cutting sleeve 175 to thusensure that tissue does not clog the lumen of the inner sleeve 175. Ascan be seen in FIG. 10A and the enlarged views of FIGS. 11A-11C, onetissue displacement mechanism comprises a projecting element 230 thatextends proximally from distal tip 232 which is fixedly attached toouter sleeve 170. The projecting element 230 extends proximally alongcentral axis 168 in a distal chamber 240 defined by outer sleeve 170 anddistal tip 232. In one embodiment depicted in FIG. 11A, the shaft-likeprojecting element 230, in a first functional aspect, comprises amechanical pusher that functions to push a captured tissue strip 225proximally from the small cross-section lumen 190B of cutting sleeve 175as the cutting sleeve 175 moves to its fully advanced or extendedposition. In a second functional aspect, the chamber 240 in the distalend of sleeve 170 is configured to capture a volume of saline distendingfluid 244 from the working space, and wherein the existing RF electrodesof the working end 145 are further configured to explosively vaporizethe captured fluid 244 to generate proximally-directed forces on tissuestrips 225 resected and disposed in lumen 160 of the cutting sleeve 175.Both of these two functional elements and processes (tissue displacementmechanisms) can apply a substantial mechanical force on the capturedtissue strips 225 by means of the explosive vaporization of liquid inchamber 240 and can function to move tissue strips 225 in the proximaldirection in the tissue-extraction lumen 160. It has been found thatusing the combination of multiple functional elements and processes canvirtually eliminate the potential for tissue clogging the tissueextraction lumen 160.

More in particular, FIGS. 12A-12C illustrate sequentially the functionalaspects of the tissue displacement mechanisms and the explosivevaporization of fluid captured in chamber 240. In FIG. 12A, thereciprocating cutting sleeve 175 is shown in a medial position advancingdistally wherein plasma at the cutting electrode edge 180 is cutting atissue strip 225 that is disposed within lumen 160 of the cutting sleeve175. In FIG. 12A-12C, it can be seen that the system operates in firstand second electrosurgical modes corresponding to the reciprocation andaxial range of motion of cutting sleeve 175 relative to thetissue-receiving window 176. As used herein, the term “electrosurgicalmode” refers to which electrode of the two opposing polarity electrodesfunctions as an “active electrode” and which electrode functions as a“return electrode”. The terms “active electrode” and “return electrode”are used in accordance with convention in the art—wherein an activeelectrode has a smaller surface area than the return electrode whichthus focuses RF energy density about such an active electrode. In theworking end 145 of FIGS. 10A-11C, the cutting electrode element 195 andits cutting electrode edge 180 must comprise the active electrode tofocus energy about the electrode to generate the plasma for tissuecutting. Such a high-intensity, energetic plasma at the electrode edge180 is needed throughout stroke X indicated in FIG. 12A-12B to cuttissue. The first mode occurs over an axial length of travel of innercutting sleeve 175 as it crosses the tissue-receiving window 176, atwhich time the entire exterior surface of outer sleeve 170 comprises thereturn electrode indicated at 185. The electrical fields EF of the firstRF mode are indicated generally in FIG. 12A.

FIG. 12B illustrates the moment in time at which the distal advancementor extension of inner cutting sleeve 175 entirely crossed thetissue-receiving window 176. At this time, the electrode sleeve 195 andits electrode edge 180 are confined within the mostly insulated-wallchamber 240 defined by the outer sleeve 170 and distal tip 232. At thismoment, the system is configured to switch to the second RF mode inwhich the electric fields EF switch from those described previously inthe first RF mode. As can be seen in FIG. 12B, in this second mode, thelimited interior surface area 250 of distal tip 232 that interfaceschamber 240 functions as an active electrode and the distal end portionof cutting sleeve 175 exposed to chamber 240 acts as a return electrode.In this mode, very high energy densities occur about surface 250 andsuch a contained electric field EF can explosively and instantlyvaporize the fluid 244 captured in chamber 240. The expansion of watervapor can be dramatic and can thus apply tremendous mechanical forcesand fluid pressure on the tissue strip 225 to move the tissue strip inthe proximal direction in the tissue extraction lumen 160. FIG. 12Cillustrates such explosive or expansive vaporization of the distentionfluid 244 captured in chamber 240 and further shows the tissue strip 225being expelled in the proximal direction the lumen 160 of inner cuttingsleeve 175. FIG. 14 further shows the relative surface areas of theactive and return electrodes at the extended range of motion of thecutting sleeve 175, again illustrating that the surface area of thenon-insulated distal end surface 250 is small compared to surface 255 ofelectrode sleeve which comprises the return electrode.

Still referring to FIGS. 12A-12C, it has been found that a single powersetting on the RF source 150 and controller 155 can be configured both(i) to create plasma at the electrode cutting edge 180 of electrodesleeve 195 to cut tissue in the first mode, and (ii) to explosivelyvaporize the captured distention fluid 244 in the second mode. Further,it has been found that the system can function with RF mode-switchingautomatically at suitable reciprocation rates ranging from 0.5 cyclesper second to 8 or 10 cycles per second. In bench testing, it has beenfound that the tissue-cutting device described above can cut and extracttissue at the rate of from 4 grams/min to 8 grams/min without anypotential for tissue strips 225 clogging the tissue-extraction lumen160. In these embodiments, the negative pressure source 125 also iscoupled to the tissue-extraction lumen 160 to assist in applying forcesfor tissue extraction.

Of particular interest, the fluid-capture chamber 240 defined by sleeve170 and distal tip 232 can be designed to have a selected volume,exposed electrode surface area, length and geometry to optimize theapplication of expelling forces to resected tissue strips 225. In oneembodiment, the diameter of the chamber is 3.175 mm and the length is5.0 mm which taking into account the projecting element 230, provided acaptured fluid volume of approximately 0.040 mL. In other variations,the captured fluid volume can range from 0.004 to 0.080 mL.

In one example, a chamber 240 with a captured liquid volume of 0.040 mLtogether with 100% conversion efficiency in and instantaneousvaporization would require 103 Joules to heat the liquid from roomtemperature to water vapor. In operation, since a Joule is a W*s, andthe system reciprocate at 3 Hz, the power required would be on the orderof 311 W for full, instantaneous conversion to water vapor. Acorresponding theoretical expansion of 1700× would occur in the phasetransition, which would results in up to 25,000 psi instantaneously(14.7 psi×1700), although due to losses in efficiency andnon-instantaneous expansion, the actual pressures would be much less. Inany event, the pressures are substantial and can apply significantexpelling forces to the captured tissue strips 225.

Referring to FIG. 12A, the interior chamber 240 can have an axial lengthfrom about 0.5 mm to 10 mm to capture a liquid volume ranging from about0.004 mL 0.01 mL. It can be understood in FIG. 12A, that the interiorwall of chamber 240 has an insulator layer 200 which thus limits theelectrode surface area 250 exposed to chamber 240. In one embodiment,the distal tip 232 is stainless steel and is welded to outer sleeve 170.The post element 248 is welded to tip 232 or machined as a featurethereof. The projecting element 230 in this embodiment is anon-conductive ceramic. FIG. 13 shows the cross-section of the ceramicprojecting element 230 which is fluted, which in one embodiment hasthree flute elements 260 in three corresponding axial grooves 262 in itssurface. Any number of flutes, channels or the like is possible, forexample from 2 to about 20. The purpose of this design is to provide asignificant cross-sectional area at the proximal end of the projectingelement 230 to push the tissue strip 225, while at the same time thethree grooves 262 permit the proximally-directed jetting of water vaporto impact the tissue exposed to the grooves 262. In one embodiment, theaxial length D of the projecting element 230 is configured to pushtissue entirely out of the reduced cross-sectional region 190B of theelectrode sleeve element 195. In another embodiment, the volume of thechamber 240 is configured to capture liquid that when explosivelyvaporized provided a gas (water vapor) volume sufficient to expand intoand occupy at least the volume defined by a 10% of the total length ofextraction channel 160 in the device, at least 20% of the extractionchannel 160, at least 40% of the extraction channel 160, at least 60% ofthe extraction channel 160, at least 80% of the extraction channel 160or at least 100% of the extraction channel 160.

As can be understood from FIGS. 12A to 12C, the distending fluid 244 inthe working space replenishes the captured fluid in chamber 240 as thecutting sleeve 175 moves in the proximal direction or towards itsnon-extended position. Thus, when the cutting sleeve 175 again moves inthe distal direction to cut tissue, the interior chamber 240 is filledwith fluid 244 which is then again contained and is then available forexplosive vaporization as described above when the cutting sleeve 175closes the tissue-receiving window 176. In another embodiment, a one-wayvalve can be provided in the distal tip 232 to draw fluid directly intointerior chamber 240 without the need for fluid to migrate throughwindow 176.

FIG. 15 illustrates another variation in which the active electrodesurface area 250′ in the second mode comprises a projecting element 230with conductive regions and non-conductive regions 260 which can havethe effect of distributing the focused RF energy delivery over aplurality of discrete regions each in contact with the captured fluid244. This configuration can more efficiently vaporize the captured fluidvolume in chamber 240. In one embodiment, the conductive regions 250′can comprise metal discs or washers on post 248. In other variation (notshown) the conductive regions 250′ can comprise holes, ports or pores ina ceramic material 260 fixed over an electrically conductive post 248.

In another embodiment, the RF source 150 and controller 155 can beprogrammed to modulate energy delivery parameters during stroke X andstroke Y in FIGS. 12A-12C to provide the optimal energy (i) for plasmacutting with electrode edge 180, and (ii) for explosively vaporizing thecaptured fluid in chamber 240.

It should be appreciated that while an RF source is suitable for causingexplosive vaporization of the captured fluid volume, any other energysource can be used and falls within the scope of the invention, such asan ultrasound transducer, HIFU, a laser or light energy source, amicrowave or a resistive heat source.

In another embodiment, the probe can be configured with a lumen incommunication with a remote liquid source to deliver fluid to theinterior chamber 240.

FIG. 16 illustrates an embodiment of a hysteroscopic system 400 forfibroid cutting and extraction that comprises a hysteroscope 50 andcutting tool 100 as describe above together with an integrated fluidmanagement system 402. The fluid management system is integrated withcontroller 150 which controls the positive pressure source 125 and thenegative pressure source 140 for controlling all inflows of distendingfluid and outflows of distending fluid. It has been found that the probe100 and internal RF cutting sleeve 175 can be extremely efficient incutting tissue slugs or strips when engaging tissue under suitableslight contacting pressure. In use, the system can cut tissue on eachextending stroke that can approximate the theoretical maximum “cutvolume”—which term I used herein to describe the cylindrical tissuevolume defined by the inner diameter of reduced cross section 190B of RFsleeve 195 and the length of the stroke (or longitudinal windowdimension) and is depicted in FIG. 17. In other words, FIG. 17illustrates the potential tissue volume that can be cut in a singleextending stroke of the cutting sleeve 175. In one embodiment, the cutvolume can comprise 55 mm³ wherein the inner bore of lumen 190B is 0.85″and the window 176 is 15 mm in length Z. In other embodiments whichstill maintain the O.D. of the outer sleeve 170 at 0.145″ or less, andby providing a larger lumen 190B, the cut volume can be at least 60 mm³,65 mm³ or 70 mm³. The definition of cut volume does not separatelydistinguish the slight thickness of tissue that is cut by the RFplasma—which is vaporized altogether.

In actual operation, the efficiency has been found to be very high,wherein the efficiency is defined as the percentage of maximum cutvolume that is cut per stroke. For example, the probe's efficiency canbe 80%, 90% or 100% on each extending stroke after which the tissue isthen extracted by means described above after extension of the cuttingsleeve 175 past the window 176.

It can be easily understood that if the cutting efficiency is very highas described above, the reduced cross section lumen 190B and extractionlumen 160 will be substantially occupied by tissue during operation andthus leave little room for distending fluid to be extracted with thetissue strips or slugs. This aspect of the invention is highlyadvantageous as the risk of intravasation can be reduced, the fluidmanagement system can be simplified and the fluid management system canbe more compact and potential well-suited for office-based proceduresinstead of hospital operating rooms.

Referring to FIG. 16, in one system embodiment with lumen dimensionsdescribed above, if the system is left “open” with the ablation probe'sworking end 145 disposed in a sealed and distended cavity 405 (e.g. auterine cavity) and the negative pressure source operated at a level ofapproximately 600 mmHg, when a suitable pressure is applied to distendthe cavity—then a flow rate will range from about 550 mL/min to 700mL/min flowing through the open system. In actual operation, it has beenfound that the efficiency of the RF cutting system can reduce theinflows to less 400 mL/min, less than 300 mL/min and as low as 200mL/min. In this system, a cervical seal 420 is used to prevent leakageof distending fluid from the cavity 422.

In general, a method of the invention for cutting and extracting tissuefrom a body cavity comprises distending a body cavity with distendingfluid inflow, cutting tissue with a reciprocating RF cutting sleeveconfigured to reciprocate and capture tissue strips in a distal portionof an extraction lumen of an elongate probe, extracting the tissuestrips and distending fluid at least in part by applying negativepressure to the extraction lumen thereby causing a distending fluidoutflow, and managing the fluid inflows and outflows with a controllerto limit distending fluid inflows to less than 400 mL/min.

In such a method, the probe can have an extraction lumen 160 that has amean diameter of at least 0.085″, at least 0.090″, at least 0.095″ or atleast 0.100″, wherein the larger lumens obviously increase thedifficulty in lowering fluid inflow rates. The method includes operatingthe RF cutting sleeve in a reciprocation range of 0.5 Hz to 4.0 Hz. Themethod allows the RF cutting sleeve to cuts tissue at the rate of atleast 2 grams/min, at least 3 grams/min or at least 4 grams/min. In thismethod, the controller can further limit the fluid inflows to less than300 mL/min, less than 250 mL/min or less than 200 mL/min.

In another variation for reducing the inflows of distending fluids, thecontroller 155 can modulates inflows and/or outflows depending on whichportion or position of the stroke of the RF cutting sleeve 175. Forexample, the controller can use maximum suction for only a selectedinitial portion of the extending stroke (e.g., 20%, 30%, 40%, 50% or60%) after which time the tissue that was suctioned into the window 176will not have time to rebound outwardly before being cut. Further, whenthe sleeve 175 is in its retraction stroke, the negative pressure can bereduced since the movement of the sleeve itself is moving the tissueproximally in the extraction lumen 160. In another variation, thenegative pressure can be pulsed.

In another variation for reducing the inflows of distending fluids intothe body cavity, the controller 155 can modulate inflows and/or outflowsin response to measured fluid pressure in the body cavity. The probe 100can carry a pressure sensor, or pressure sensor can be introducedthrough the hysteroscope. In another variation, the controller canmodulate inflows and/or outflows at least in part in response to ameasured negative pressure in communication with the extraction lumen.In another method, the controller 155 can compare intracavity pressureand applied negative pressure and modulate either inflows or outflownegative pressure.

In general, a method of cutting and extracting tissue from a body cavitycomprises distending a body cavity with distending fluid inflow, cuttingtissue with a reciprocating RF cutting sleeve configured to reciprocateand capture tissue strips in a distal portion of an extraction lumen ofan elongate probe, extracting the tissue strips and distending fluid atleast in part by applying negative pressure to the extraction lumenthereby causing a distending fluid outflow, and modulating at least oneof an inflow rate or an outflow rate in response to feedback from asensor system. The sensor can be configured to measure pressure in thebody cavity, to measure negative pressure coupled to the extractionlumen, or to compare pressure in the body cavity and the negativepressure coupled to the extraction lumen.

In another aspect of the invention, a method of cutting and extractingtissue from a body cavity comprises distending a body cavity withdistending fluid inflow, cutting tissue with a reciprocating RF cuttingsleeve configured to reciprocate and capture tissue strips in a distalportion of an extraction lumen of an elongate probe, extracting thetissue strips and distending fluid at least in part by applying negativepressure to the extraction lumen thereby causing a distending fluidoutflow; and modulating at least one operational parameter in responseto feedback signals from sensors coupled to a controller. Theoperational parameters can be selected from the group consisting ofapplied RF power, fluid inflow rate, fluid inflow pressure,reciprocation rate and negative pressure coupled to the extractionlumen. The feedback signals can be selected from the group consisting ofimpedance, capacitance of compositions in the extraction lumen, fluidpressure level in the body cavity, reciprocation rate and negativepressure level in the extraction lumen.

In another aspect of the invention, referring to FIG. 17, a medicalsystem for cutting and extracting tissue form a body cavity comprises aprobe comprising a windowed outer sleeve and a concentric inner RFcutting sleeve that defines a per stroke cutting volume of at least 50mm³, and a fluid management system comprising a distending fluid source,a pump mechanism and a controller for controlling inflows and outflowsof a distending fluid from the body cavity, wherein the fluid managementsystem is configured to deliver a distension fluid volume of less than400 mL/min, less than 300 mL/min or less than 200 mL/min. In anothervariation, the RF cutting sleeve defines a per stroke cutting volume ofat least 55 mm³, 60 mm³, 65 mm³ or 70 mm³. The reciprocation of the RFcutting sleeve can be in the range of 0.5 Hz to 4.0 Hz.

In general, a medical system of the invention for cutting and extractingtissue form a body cavity comprises a probe comprising a windowed outersleeve and a concentric inner RF cutting sleeve configured to cut tissueat a rate of at least 3 grams/min, and a fluid management systemcomprising a distending fluid source, a pump mechanism and a controllerfor controlling inflows and outflows of a distending fluid from the bodycavity, wherein the fluid management system is configured to deliver adistension fluid volume of less than 400 mL/min, less than 300 mL/min orless than 200 mL/min.

FIGS. 18-19 illustrate a fluid management system 500 that can be usedwhen treating tissue in a body space, cavity or potential space, and isdepicted schematically in a hysteroscopic system embodiment for cuttingand extraction of fibroids or other abnormal intra-uterine tissue. Abody cavity or uterine cavity 422 is shown with a cervical seal 420positioned in the external cervical os and cervical canal. The fluidmanagement system 500 again is integrated with a controller 155 that isconfigured to control the positive pressure source 125 (or pump 125′)and the negative pressure source 140 (or pump 140′) for controllinginflows of distending fluid from source 120 and outflows of suchdistending fluid. In this embodiment, a probe 100 is shown with theworking end 145 disposed in the uterine cavity 422.

Referring to FIG. 18, in general, the fluid management system 500 of theinvention comprises a source or container 120 of distending fluid, apumping system for maintaining the distension of a body cavity, a filtersystem 510 for filtering distending fluid that is recovered from thebody cavity and a further subsystem for returning the filtered fluid tothe source 120. The use of such recovered and filtered fluid and thereplenishment of the fluid supply 120 is advantageous because (i) theclosed-loop fluid management system 500 system can effectively measurefluid deficit to thereby monitor intravasation to thereby insure patientsafety, (ii) the system can be set up and operated in a much moretime-efficient manner that prior art fluid deficit monitoring systems,and (ii) the system can be very compact and less expensive to enableoffice-based procedures.

FIG. 19 illustrates the fluid management system 500 in more detailwherein a first pump 125′ provides an inflow of a distending fluid fromfluid source 120 into the body cavity or potential space 422 at asuitable rate, e.g., ranging from 200 mL/min to 750 mL/min. The systemhas a second pump 140′ to assist in removing and recovering fluidremoved from space 422. A tissue collection reservoir 515 collectsresected tissue strips. Thereafter, the recovered fluid is moved by pump140′ into the filter system 510. More in particular, the filter system510 comprises a first filter 520 or macrofilter that accommodates highflows from about 200 mL/min to 2000 mL/min and is adapted for removingcells and particulate matter from the fluid flow. In one variation, thefirst filter 520 has pore size of about 10 microns, 5 microns or 1micron. As can be seen in FIG. 19, the second filter or microfilter 525is a low volume filter for use in ultra-filtration of fluids as is knownin the art and is adapted for the removal of molecules having a weightgreater than 100 kD or 50 kD. The debris or blood constituents filteredfrom the microfilter is collected in blood collection reservoir 528(FIG. 19). In one variation, a pump 530 is provided for a looped flowthrough the microfilter 525 to cleanse the distending fluid forsubsequent return to the fluid source or container 120.

In general, the fluid management system 500 corresponding to theinvention comprises a first pump for providing an inflow of a distendingfluid from fluid source 120 to the body cavity or potential space, asecond pump for removing and recovering fluid removed from the space anda controller and filter system for filtering recovered fluid andthereafter re-circulating the filtered fluid to the fluid source 120.

In one embodiment, the fluid management system 500 has a controllerconfigured for operation in a pressure control mode wherein the firstand second pumps cooperate to deliver fluid to the space or cavity 422(FIGS. 18-19) and maintain pressure therein within a predeterminedpressure range. In another variation, the fluid management system has acontroller configured for operation in a flow control mode wherein thefirst and second pumps cooperate to deliver fluid to the space within apredetermined flow rate range.

The fluid management system 500 of FIGS. 18-19 can utilize at least onepressure sensor capable of providing a pressure signal indicating fluidpressure in the space 422 to enable or assist in operating in variousmodes, for example, the pressure mode or the flow control mode. Thepressure sensor can be disposed in an inflow lumen that delivers thedistending fluid inflow. In another variation, the pressure sensor canbe disposed in a lumen that receives the distending fluid outflow.

In one embodiment, the fluid management system has a controller 155configured for calculation of a fluid deficit that is measured as adifference between a fluid volume delivered to the space 422 and a fluidvolume recovered from the space (see FIG. 18). The controller 155 can beconfigured to compare pressure signals from at least two pressuresensors, wherein the controller is further configured to terminate orstop the pump if two pressure signals differ by a predetermined minimumamount.

In another embodiment, the fluid management system includes a disposabletubing set for delivering fluid to a probe or hysteroscope introducedinto the space 422, wherein the tubing set includes at least one pulsedampener for use with a peristaltic or other pump (not shown).

In another aspect of the invention, a method of monitoring a fluiddeficit is provided in the use of a fluid management system in atreatment in a body space which comprises (i) recording an initialreference volume comprising a volume of distending fluid containedwithin a supply container, a system capacity volume, and a volume of thespace, (ii) inflowing distending fluid into the space, recovering afluid volume in an outflow from the space and re-circulating therecovered fluid to the supply container to provide a replenished volume,and (iii) calculating the fluid deficit by subtracting the replenishedvolume from the initial reference volume. The recording step can includepriming a supply tubing set and a surgical device with the distendingfluid. In another variation, the recording step includes inflowingdistending fluid into the body space 422, and/or calculating the volumeof the body space by imaging means. The method can further comprisessealing an access to the body space 422 to prevent the loss ofdistending fluid into the environment, such as in the use of a cervicalseal. In another variation, the method can capture fluid loss throughthe access to the body space, measure such lost fluid volume, andcalculate the fluid deficit taking into account the lost fluid volume. Auser interface is provided in the controller 15 to monitor and signalone or more fluid deficit parameters on an intermittent or continuousbasis—wherein the signal can be at least one of visual, aural andtactile.

Referring again to FIG. 18, a method of using a fluid management systemin a treatment in a body cavity comprises actuating a first pump todeliver a distending fluid volume from a fluid source into the cavity,actuating a second pump to remove and recover fluid from the cavity,filtering the recovered fluid and re-circulating filtered fluid to thefluid source. The controller is adapted to operate in a first mode formaintaining distension of the cavity wherein fluid pressure ismaintained in the cavity 422 in a predetermined range. In one variation,the predetermined range is between 20 mmHg and 200 mmHg. In anothermethod, the controller operates in second mode configured to maintain aninflow rate in a predetermined range, wherein the range is between 200mL/min and 1000 mL/min. In one variation, the filtering step includesflowing the recovered fluid through a first filter mechanism to removematter having mean cross section of 1 micron and larger. The filteringstep further includes flowing the recovered fluid through at least asecond filter mechanism to remove molecules having a weight greater than50 kD. A pump 530 can be provided to generate a pressure of at least 10psi, 20 psi, 30 psi or 40 psi for re-circulating a portion of the fluidoutflow through the at least one second filter mechanism. In onevariation, the system can return filtered fluid to the distending fluidsource 120 with a fluid recovery rate of at least 400 mL/min, 500mL/min, 600 mL/min, 700 mL/min or 800 mL/min.

In one embodiment, the fluid management system 500 of FIG. 18 comprisesa first pump for delivering a distending fluid to a body space through aprobe, a second pump for providing fluid outflows from the space througha probe extraction lumen, and a controller operatively connected to thefirst and second pumps and the probe wherein the controller isconfigured to modulate the pumps to maintain a fluid pressure in thespace in response to an indicator signal that indicates the extractionlumen is in an open, partly open or closed configuration. In thisembodiment, the probe includes a windowed outer sleeve and a concentricreciprocating inner cutting sleeve wherein reciprocation of the cuttingsleeve adjusts the extraction lumen between the open, partly open orclosed configurations. Thus, the controller can reduce needed flowsthrough the system by reducing at least one flow pressure (at pump 125′or 140′ in FIG. 19) when the window is open and increasing at least oneflow pressure when the window is closed. In another variation, the flowfrom either pump 125′ or 140′ can be pulsed.

In another variation of fluid management system, the system can compriseat least one pump for delivering a distending fluid to a body spacethrough a probe and for providing fluid outflows from the space througha probe extraction lumen, wherein the probe comprises a windowed outersleeve 170 and a reciprocating inner cutting sleeve 175 (FIGS. 11A-11C)wherein such reciprocation moves the probe between window-open andwindow-closed configurations and wherein a window-closing mechanism isprovided to move the probe to the window-closed configuration inresponse to idling the reciprocation. This system will assist inmaintaining distension of the body cavity while at the same timereducing the total volume of new fluid used in a procedure. In anothervariation, the window-closing mechanism includes a stroke sensingmechanism operatively connected to the cutting sleeve 175 fordetermining the stage of a reciprocating stroke of the cutting sleeve.

In another variation, the probe working end comprises a windowed outersleeve and a reciprocating inner cutting sleeve wherein suchreciprocation moves the probe between window-open and window-closedconfigurations and a controller and sensor system configured to signalif the probe working end is engaging tissue, and a controller algorithmconfigured to modulate the at least one pump in response to the signal.In one variation shown in FIG. 20, the sensor system comprises at leastone capacitance sensor 545 at the edge of the window 176 on sleeve 170which can measure a change in capacitance and compare capacitanceagainst a stored library of values to determine whether the working end550 is engaging tissue or is only submersed in the distending fluid. Inresponse to the signal, the fluid management system can modulate and/orreduce flow pressures when the working end is not engaging and cuttingtissue. In another variation, the capacitance sensor(s) could bepositioned on the cutting sleeve 175. In other embodiments, the sensorsystem can be configured to function as described above, wherein thesensor system can be configured to measure impedance associated with atRF cutting sleeve, can be configured to measure pressure of comparepressures, or can be configured to measure loads on the cutting sleevewith a load sensor.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration and the above description of theinvention is not exhaustive. Specific features of the invention areshown in some drawings and not in others, and this is for convenienceonly and any feature may be combined with another in accordance with theinvention. A number of variations and alternatives will be apparent toone having ordinary skills in the art. Such alternatives and variationsare intended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

What is claimed is:
 1. A method of monitoring delivery and recovery of adistension fluid to detect loss during treatment of a body or potentialspace, said method comprising: recording a reference volume ofdistending fluid contained within a supply container; supplying aninflow of distending fluid into the body or potential space; recoveringan outflow of distending fluid from the body or potential space;filtering the recovered distending fluid; and re-circulating therecovered fluid to the supply container to provide a replenished volume;and calculating a fluid deficit by subtracting the replenished volumefrom the initial reference volume.
 2. The method of claim 1, wherein therecording step further comprises: recording a system capacity volume anda volume of the body or potential space.
 3. The method of claim 2,wherein the recording the system volume includes priming a supply tubingset and a surgical device with the distending fluid.
 4. The method ofclaim 2, wherein the recording the volume of the body or potential spaceincludes inflowing distending fluid into the body or potential space. 5.The method of claim 1, wherein the recording step includes calculatingthe volume of the body or potential space by imaging means.
 6. Themethod of claim 1, further comprising: sealing an access to the body orpotential space to prevent loss of distending fluid into an adjacentenvironment.
 7. The method of claim 6, further comprising: capturingfluid loss through the access to the body or potential space andmeasuring such lost fluid volume.
 8. The method of claim 7, whereincalculating the fluid deficit comprises accounting for the lost fluidvolume.
 9. The method of claim 1, wherein a control system monitors andsignals a fluid deficit parameter on an intermittent or continuous basisvia a user interface.
 10. The method of claim 9, wherein the signal isat least one of visual, aural, and tactile.
 11. The method of claim 10,wherein the control system periodically or continuously calculates thefluid deficit, wherein the control system activates the signal if thefluid deficit exceeds a predetermined limit.
 12. The method of claim 9,wherein the control system continuously or periodically compares aninflow pressure and an outflow pressure and wherein the controller isfurther configured to stop the inflow of distending fluid into the bodyor potential space if two pressure signals differ by more than apredetermined minimum amount.
 13. The method of claim 1, whereinfiltering the recovered distending fluid includes passing the recovereddistending fluid through a filter arrangement for removing waste fromthe recovered distending fluid before re-circulating the recovered fluidto the supply container.
 14. The method of claim 1, further comprising:controlling the inflow of distending fluid and/or the outflow ofdistending fluid to maintain a pre-selected volume of distending fluidwithin the body or potential space.
 15. The method of claim 14, furthercomprising: terminating the inflow of distending fluid if thepre-selected volume of distending fluid within the body or potentialspace is exceeded for a predetermined amount of time or by apredetermined value.
 16. The method of claim 1, further comprising:maintaining a distending fluid pressure within the body or potentialspace within a predetermined pressure range.
 17. The method of claim 16,further comprising: terminating the inflow of distending fluid if thedistending fluid pressure within the body or potential space exceeds thepredetermined pressure range.
 18. The method of claim 16, furthercomprising: increasing the inflow of distending fluid if the distendingfluid pressure within the body or potential space falls below thepredetermined pressure range.
 19. The method of claim 16, wherein atleast one pressure sensor is disposed in fluid communication with thebody or potential space.
 20. The method of claim 1, further comprising:resecting tissue within the body or potential space using a tissueresection device extending into the body or potential space.